The present invention is directed to a process for transferring self-assembled monolayers onto solid substrates for use as, for example, etching masks.
Particle self-organization at aqueous interfaces has been of scientific interest for several decades. Interfacial self-assemblies at nanometer and micrometer scales can be used to generate micropatterned solid surfaces, which have potential applications in microelectronic and display fabrication, optoelectronic devices, biological microanalysis, etc. Langmuir-Blodgett techniques have been used to deposit hexagonally close-packed (HCP) monolayers of particles formed at aqueous interfaces onto solid substrates. HCP monolayers can also form and be deposited onto substrates during the evaporation of aqueous particle suspensions. Increases in surface pressure or capillary attraction, or both can be responsible for forcing particles to pack in the most spatially economical way during these events.
U.S. Pat. No. 6,818,117 to Ferguson et al discloses a method of preparing self-assembled monolayers on a metal by electrolyzing a thiosulfate compound in a solvent where the electricity for the electrolysis is applied at a voltage for a period of time.
Nanometer- and micrometer-sized charged particles at aqueous interfaces experience long-range Coulombic repulsion and capillary attraction. The interplay of the repulsive and attractive forces results in a variety of self-assembly modes. For example, charged particles at an aqueous interface self-organize into hexagonal arrays directed by long-range electrostatic repulsion and capillary attraction between neighboring particles. Within confined space, large two-dimensional HCP crystals can form, and control of the lattice constant and even distortion from the HCP lattice type can be effected by the variation of the surface pressure. In fact, the ability to adjust the lattice constant to lengths greater than the particle diameter could often be critical for many of the above perceived applications. The transfer and immobilization of two-dimensional sub-monolayer HCP crystals with lattice constants larger than the particle diameter is challenging because the particles are not physically touching each other and can easily be moved out of their lattice positions.